George Washington University, which U.S. News & World Report had ranked 51st among national universities, is now unranked after the school’s disclosure last week that it had overstated the academic credentials of incoming freshmen.

On Wednesday, the architect of the U.S. News Best Colleges listings, Robert Morse, wrote that GWU will remain unranked until the next rankings are issued in September and the university confirms the accuracy of data it submits.

The U.S. News action — effectively, a temporary demotion for GWU in the pecking order of higher education — represented a significant public relations setback for a university that in recent decades has sought to raise its reputation.

Many GWU students prize its location a few blocks from the White House and its status as an upper-tier school that had been no lower than 54th on the U.S. News list for a decade. Such prestige, students said, has made the school worth the annual sticker price of more than $45,000 a year in tuition and fees.

News of the de-ranking caused mass anger on campus.

“Every single person I’ve seen is furious,” said Hugo Scheckter, 21, a senior. “A lot of people pay a lot of money to come here, thinking they’ll get a degree from a top 50 university.”

On Twitter, the hashtag #GWU lit up with criticism from students and alumni and with calls for the administration to explain itself.

GWU President Steven Knapp, who revealed the flaw in admissions data last week and expressed regret for what he called an error, said the university was surprised by the U.S. News decision to remove the ranking rather than correct it. “How people interpret this, being out of the rankings for a year, I don’t know,” Knapp said.

He said the university is committed to honest and transparent reporting. “You’ve got to do it no matter what you think the consequences might be,” he said.

Two other prominent schools, Claremont McKenna College in California and Emory University in Atlanta, acknowledged this year that they inflated SAT scores of incoming freshmen in public reports. But U.S. News concluded in both cases that the 2011-12 rankings of the two schools were not affected.

At issue with GWU is the percentage of freshmen in fall 2011 who were said to have graduated in the top 10 percent of their high school class. Originally, the university said the share was 78 percent. But GWU officials said last Thursday that the correct figure was 58 percent.

That share, they said, was based on the 38 percent of incoming students for whom class-rank information was available. In recent years, a growing number of high schools have stopped providing class rankings to colleges, raising questions about the value of the statistic.

The problem, officials said, was that the university made internal estimates of how many students without official class-rank data were likely to have been in the top 10 percent of their classes. Then, officials said, those estimates were mistakenly combined with documented class-rank figures.

Questions were raised about the data in August during an internal management review. The school then asked an independent auditor, Baker Tilly, to take a closer look.

Officials said that the university and the auditor found no evidence of malicious intent by personnel responsible for the data reporting. The university is recruiting for a senior associate provost for enrollment management — a position intended to strengthen oversight of admissions data.

The class-rank statistic accounts for 6 percent of a school’s score under the U.S. News ranking formula. Other factors include graduation and student retention rates, reputation for undergraduate education based on surveys of academic leaders, financial resources and alumni giving. Critics call the formula arbitrary and say U.S. News wields too much influence over how universities are run and how parents and students choose a college.

For six days, GWU had awaited a verdict from U.S. News on what the correction to its admissions data would mean. Initially, Morse, who is director of data research for U.S. News, said that if there were any change to the school’s ranking it would be slight.

Morse declined to elaborate Wednesday on his thinking beyond an item he wrote on the U.S. Newsblog Morse Code. In the item, he wrote that GWU’s initial ranking this year of 51st was “higher than it otherwise would have been” given the university’s disclosure.

Jason Haber, 35, who graduated from GWU in 1999, said rankings have always been a topic at the school. He recalled that in the late 1990s, the school took pride that it reached the top 50 on the U.S. News list. A year ago, it ranked 50th. Now, it is unranked. But Haber said many GWU alumni are taking it in stride.

“Everyone is laughing about it. No one is walking around depressed, [saying,] ‘My degree is worth nothing,’ ” Haber said.